Thread: Stihl brushcutter problems

Originally Posted by mick88

Before you play with the carby screws drain the fuel out and mix up some new fresh fuel to the exact ratio. Most small engine two stroke issues are with fuel going stale or incorrect mix. Not mixture/air screws altering. Make sure the nylon is not too long as that will make it labour. Also check the exhaust for any carbon build up and burn it out if necessary.
Good luck.


Cheers, Mick.

Its got fresh fuel in it, only a couple of days old....

Originally Posted by Railey

Try taking the muffler off and checking for clogs. Then look at the exhaust port on the motor. Sometimes they get gummed up with soot and will cause all sorts of bogging.....


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a little bit of soot, but clear

Originally Posted by robbotd5

Does it have the one piece fuel delivery/return black rubber tubing?.
I had the same issues with mine. Turned out to be a perished fuel delivery tube making the mixture too lean. I ended up just using some aquarium air tubing to replace the inlet/return and have not had an issue since. I was a little dubious about the compatibility of the tubing with fuel but so far, all good.
Regards
Robbo

its got 3 seperate hoses running to the tank

Originally Posted by bee utey

The one way air inlet valve on the filler cap may be too tight, rubber gone a bit hard. Unscrew the cap for a second while its bogging down and see if it picks up. I had this problem with a new brush cutter recently, I stuck a sharp knife in the valve and reduced its tightness a bit. Works perfectly now.

I'll try popping the cap next time it plays up

Check all the crankcase bolts are tight.

My stihl brushcutter was giving trouble a while ago due to a blocked muffler.
Take the exhaust off, soak it in petrol and then light it to burn off the excess oil inside it. If this makes no effect you then probably have a carby problem with dirt in a jet somewhere.

How old is it? My money is on carb diaphragms and or leaky crank seal fuel hoses should be supple not hard and brittle or rotton

fuel hoses are fine, and same for the muffler